Pure maths, physics, logic (braingames.ru): non-trade-related brain games - page 197

 

To keep things interesting I am posting another challenge:

There are truth-tellers and liars on the island. The former always tell the truth, the latter always lie. Every inhabitant of the island lives in a four-storey house. All the islanders took part in a sociological survey. To the question "Do you live on the ground floor?" 40% of the residents answered "yes". A similar question about the first floor was answered affirmatively by 30%, about the third floor by 50% and about the fourth floor by 0%. What percentage of islanders actually live on the ground floor?

The weight is 3. The task can be found here.

Задачи, загадки, логические игры [Игры разума] икф
  • www.braingames.ru
На острове живут правдивцы и лжецы. Первые всегда говорят правду, вторые всегда лгут. Каждый житель острова живет в четырехэтажном доме. В социологическом опросе приняли участие все жители острова. На вопрос «Вы...
 
Mathemat:

To keep things interesting, I am posting another challenge:

There are truth-tellers and liars on the island. The former always tell the truth, the latter always lie. Each inhabitant of the island lives in a four-storey house. All the islanders took part in a sociological survey. To the question "Do you live on the ground floor?" 40% of the residents answered "yes". A similar question about the first floor was answered affirmatively by 30%, about the third floor by 50% and about the fourth floor by 0%. What percentage of islanders actually live on the ground floor?

The weight is 3. The task can be found here.

only liars definitely live on the fourth floor
 
Mathemat:
Liars 10%
 
TheXpert:
Liars are 10%.
If this is the answer to the problem, then it turns out that these 10% to the question "Do you live on the fourth floor?" should have answered "Yes" - i.e. lied. But we know that 0% answered "Yes" to the fourth floor.
 
TheXpert:
Liars are 10%.
Yes, liars are definitely 10%. The rest is obvious.
 
Yeah. Liars are 10%. Resolved.
 

There are 13 candles in the magical candlestick, arranged in a circle. Some of them are lit. The magic is that if you light or extinguish one candle, two neighbouring candles will also change their state: the unlit ones will light up and the burning ones will go out. Is it always possible to get all the candles to burn at the same time?

Weight - 3. The task is here.

Задачи, загадки, логические игры [Игры разума] икф
  • www.braingames.ru
В магическом подсвечнике 13 свечей, расположенных по кругу. Некоторые из них горят. Магия в том, что если зажечь или потушить какую-то свечу, две соседние тоже поменяют свое состояние: незажженные загорятся, а горящие потухнут. Всегда ли можно добиться того, чтобы все свечи горели одновременно?
 

The problem seems to be solved only when the number of candles is a multiple of 3, i.e. either 12 or 15.

With 13 candles there is no solution.

 
VNIK:

The problem seems to be solved only when the number of candles is a multiple of 3, i.e. either 12 or 15.

With 13 candles there is no solution.

There are nuances. Think again.

In principle the moderator has already admitted that I solved it, but not very nice. After a suggestion to look for a more elegant solution, I agreed.

 
Mathemat:

There are nuances. Think again.

In principle, the moderator has already acknowledged that I have solved it, but not very nicely. After a suggestion to look for a more elegant solution, I agreed.

It is possible if in the first arrangement one of 13 candles is already burning (or 4 or 7 or 10 in a row), then there is a simple solution. But if all the candles are extinguished at the beginning, it's unlikely.... There must be an extra trick here, as the initial condition is too vague: "As in life - anything is possible! "

Reason: